This invention relates to an air separation system that is used to obtain a relatively pure stream of nitrogen from a feed stream of air under pressure in a pressure swing adsorption cycle.
There are, today, many methods and corresponding apparatus for carrying out the process of pressure swing adsorption or PSA. In the use of PSA technology, a stream of gas, normally air, is separated into one of its components by passing that air over a bed of adsorptive material.
Most systems include the use of two or more adsorption beds or columns and which are taken through various steps of pressurization, adsorption, depressurization and regeneration, in many sequences of steps. Such systems can be fairly complex in construction and operation and the associated timing steps, valve operation and sequencing can be considerably costly and difficult to construct. Typical examples of such systems include those shown and described in U.S. Pat. No. 3,086,339 Skarstom showing a three bed system, U.S. Pat. No. 3,891,411 with a two bed system and recently issued U.S. Pat. No. 4,892,566, Bansel et al utilizing a single bed system. Separation of nitrogen from air is also disclosed in the AICHE Journal, Apr. 1987, Vol. 33, No. 4, pages 654-662.